1. Field of the Invention
The present invention related to a closed circuit rebreather wherein the carbon dioxide (CO2) scrubbing material is imbedded within a body worn vest in order to minimize the profile of the rebreather as well as to use the natural breathing rhythm of the user to assist in the function of the rebreather.
2. Background of the Prior Art
Rebreathers are used in a wide variety of applications including military settings, especially underwater teams that desire to remain stealth and not have air bubbles surface as would be the case if using open circuit breathing apparatus. Other applications include mine rescue or other industries where poisonous gas may be present or oxygen absent, manned space vehicles and space suits where a person is effectively in a vacuum, hospital anesthesia breathing systems that supply appropriately proportioned gas mixtures to a patient without letting the gas escape to be breathed by hospital personnel, submarines, and oxygen hyperbaric chambers, among other applications.
The rebreather works by recirculating exhaled air from the user's breath based on the fact that a person only absorbs about 25 percent of the available oxygen with each breath. The exhaled air passes through a scrubbing material, such as soda lime, wherein the carbon dioxide is removed. Additional oxygen and/or a diluent is added to the circuit either manually or via an electronic system that senses for the oxygen concentration using appropriate sensors such as oxygen sensitive electro-galvanic fuels cells that calculate the oxygen concentration in the breathing loop. The scrubbing material is held within a canister that is worn about the body of the person. The breathing air within the loop moves into and out of the canister through the small pressure changes generated through respiration by the user. While extremely useful, current rebreathers suffer from certain limitations. The large mounted scrubbing canister is cumbersome to wear and throws the overall weight distribution of the wearer far off from ideal. A land-based user finds such large canisters and the uneven weight distribution occasioned by the canisters to impede maneuverability and increase overall fatigue. Water-based users find that the canisters change the natural contours of the body so as to make the user less hydrodynamic via increased drag which decreases swimming speed and also increases fatigue. If the underwater user is scooter-based, the increased profile provided by current rebreathers increases overall drag which decreases scooter performance and decreases battery life. If a water-based user transitions to land, the uneven weight loading provided by the rebreather makes the transition awkward at best. Additionally, the diver is subject to hydrostatic loads due to the extra force required to breathe into a counter-lung above or exhale into a volume below the diver's chest.
What is needed is a rebreather that addresses the above-mentioned shortcoming in the art by providing a closed circuit rebreathing system that does not rely on a large carbon dioxide scrubbing canister that affects the natural contours of the user and that does not greatly alter the overall weight distribution load upon the wearer. Such a rebreather should allow the counter-lungs used by a rebreather to be essentially at chest level in order to permit the user to breath without the need to exert substantial additional breathing pressure. Ideally, such a rebreather will be of relatively simple design and construction and be easy to use and maintain.